It is widely performed that a plurality of electronic device units having similar configurations and functions are used and controlled by a common control unit (a controller or a personal computer) and data collected from them is processed.
For example, when the shape of a cam shaft being a part of an engine of an automobile is measured, it is necessary to measure the displacement according to the rotation angle of each cam provided on the cam shaft.
In this case, conventionally, probes of detectors 111 to 114 connected to a plurality of measuring electronic device units 101 to 104 respectively are made individually to abut on cam surfaces of cams 121 to 124 of a cam shaft 120 and the detectors 111 to 114 are secured on a line that is parallel to the axis of the cam shaft 120 and separated from the axis by a fixed distance, as shown in FIG. 11.
The measurement is performed by inputting a pulse signal generated for every fixed rotation angle of the cam shaft 120 into a controller 150 from an encoder 140 attached to a motor 130 for rotating the cam shaft 120, separately inputting positional signals detected by the measuring electronic device units 101 to 104 into the controller 150 so that the controller 150 stores the positional signals for the cams 121 to 124 for every fixed rotation angle of the cam shaft 120 so as to observe the changes in the positional signals.
However, in this arrangement, the controller 150 directly controls the measuring electronic device units 101 to 104 and separately collects the positional signals detected by the units, resulting in increased load on the controller 150 and many connection lines to the measuring electronic device units 101 to 104.
Hence, it is conceivable to regard the measuring electronic device unit 101 at the head as a parent device and connect to the parent device in series the other electronic device units 102 to 104 as child devices, so that the controller 150 directly transmits/receives data only to/from the measuring electronic device unit 101 being the parent device, whereby measurement data of the electronic device units 102 to 104 being child devices can be collected through the parent device.
In this case, it is necessary to set individual identification codes (hereinafter referred to as “IDs”) in the measuring electronic device units 101 to 104 so that the controller 150 can send an instruction while identifying each of the measuring electronic device units 101 to 104 and collect the measurement data.
Conventional methods employed as a method for setting a plurality of electronic device unit IDs as described above include a method of setting the IDs by hand in a hardware setting means such as a DIP switch provided in each of the electronic device units, and a method of software setting of the IDs by an operator through key input.
The setting of IDs by the methods as described above, however, requires much labor, and the hardware setting of IDs leads to increased cost. In addition, both cases may have a problem of occurrence of setting mistakes such as setting errors or the double settings of IDs. Further, when the electronic device units constituting the system are replaced, added, or deleted, IDs need to be set again, bringing about a problem of troublesome operation for the setting.
Hence, there is a method of previously providing unique IDs to the individual electronic device units, which method has the problem of requiring the operation of registering their IDs in an external device such as a controller or a personal computer which controls the electronic device units, and the problem of, when the electronic device units constituting the system are replaced, added, or deleted, having to set changed IDs again in the external device with every change.